Subject-matter, scope and second medical use - defining double-patenting

10 minute read
21 May 2014

In a recent Technical Board of Appeal decision, the European Patent Office (EPO) has shed some light upon the boundaries of the prohibition against double-patenting.


On 12 July 1999, The Board of Regents of the University of Texas System (UTS) made an application (application number 99940802.4) for a patent related to uses of antibodies to aminophospholipids for cancer treatment. This application was granted on 22 September 2004 as European patent EP 1 096 955 B1 (EP1).

On the same date, UTS also applied for a divisional patent of EP1 under application number 04007843.8. This divisional was subsequently published as EP 1 520 588 A2 (EP2) and also related to uses of antibodies to aminophospholipids for cancer treatment.

During prosecution of EP2, the question arose before the EPO as to whether it could now grant EP2 or whether it was prohibited from doing so by the rules against double-patenting. This would all hinge upon the formulation of claims in EP1 and EP2.

Purpose-limited process versus purpose-limited product claims

The claims in EP2 and EP1 were clearly similar, but their specific language was crucial.

EP1 contained Swiss-type claims, namely a form of purpose-limited process claim formatted in accordance with decision G 5/83 of the Enlarged Board of Appeal (OJ EPO 1985, 64). Swiss-type claims typically use wording in the form of "Use of X for the manufacture of a medicament for the treatment of Y".

In contrast, EP2 contained purpose-limited product claims formatted under Article 54(5) of the European Patent Convention 2000 (EPC). Such claims usually take the form of "X for use in the treatment of Y".

First instance decision

On 27 March 2012, the examining division of the EPO heard proceedings regarding whether it could grant EP2.

As the examining division noted, the EPO will not allow two applications (or a granted patent and an application) from the same applicant to claim the same subject-matter, even if they are expressed in different words. As set out in the EPO's Guidelines for Examination, the two sets of claims applied for must be clearly distinguishable from each other for the applicant to succeed.

The key words here were "the same subject-matter" and this is a point the appeal ultimately turned upon.

The examining division found that previous authority dictated that "a claim directed to a second or further medical use claim under Article 54(5) EPC is considered to be directed to the same subject-matter as a Swiss type claim directed to the same medical use, in the sense that both these claims concern the same invention claimed in a different format".

Accordingly, the examining division held that EP1 and EP2 related to the same subject-matter and on that basis EP2 was refused for double-patenting.

The appeal

UTS therefore appealed the decision of the examining division to the Technical Board of Appeal (the Board), arguing that the examining division should have considered the scope of the claims in EP1 and EP2 when considering if they related to the same subject-matter.

On 30 January 2014, the Board gave its decision (case number T1780/12). In short they allowed the appeal and considered that there had been no double-patenting. How they reached this decision sheds some light on the boundaries of double-patenting and highlights the difference between purpose-limited process claims and purpose-limited product claims.

The same subject-matter

In its decision, the Board turned again to the EPO's Guidelines for Examination. The Board seized upon the requirement that for double patenting to be found a parent and divisional applications must not claim "the same subject-matter". The Board noted that this requirement had been upheld in several recent decisions (T 1391/07, T 877/06, T 2402/10).

The first issue for the Board was what was the meaning of subject-matter?

In decision G 2/88 (OJ EPO 1990, 93) the Enlarged Board of Appeal considered that: "the subject-matter of a claimed invention involves two aspects: first, the category or type of the claim, and second, the technical features, which constitutes its technical subject-matter." With this definition in hand the Board found that the examining division had been correct in finding the EP1 and EP2 related to the same invention.

However, that did not necessarily mean that they claimed the same subject-matter. Both EP1 and EP2 concerned the same compound and same therapeutic use, but EP1 also concerned the manufacture of a medicament which EP2 did not.

The relevance of scope

The Board also found that to determine the claimed subject-matter they must also look to the scope of protection conferred by claims. Following decision T 1391/07, double-patenting would be confined to claims conferring "notionally the same scope of protection" and could not be invoked if the scopes of protection of the two sets of claims overlapped only partially.

The purpose-limited process claims of EP1 and the purpose-limited product claims of EP2 were different formulation of claims and so fell in to different categories.

The Board noted that it is generally accepted that a claim to a method, use or process confers less protection than a product claim. A purpose-limited process claim would confer less protection than a purpose-limited product clam. The two different forms of claims in EP1 and EP2 therefore had noticeably different scopes of protection.

The Board also noted that Article 54(5) had been introduced to the EPC in an effort to overcome some of the questions raised as to whether Swiss-type claims are valid (see for example decision G 2/08 of the Enlarged Board of Appeal). The intention of the legislator in creating Article 54(5) was to provide a format for claims that would be equivalent to the case law derived Swiss-type purpose-limited process claims (see discussion of the Enlarged Board of Appeal in decision G 02/08).

However, in decision T 250/05 the Enlarged Board of Appeal had refused to allow a claim to be changed from a Swiss-type to an Article 54(5) format. In doing so, the Enlarged Board had shown that it considered that an Article 54(5) format claim had a different scope than a Swiss-type claim.

On these findings an Article 54(5) purpose-limited product claim and a Swiss-type purpose-limited product claim would not relate to substantially the same subject-matter.

Accordingly, EP2 was not prohibited by double-patenting and the Board therefore remitted the case back to the examining division for further prosecution.


The question before the Board hinged on how "the same subject-matter" was to be defined. Linked to this was the question of whether Article 54(5) purpose-limited process claims would cover the same subject-matter as Swiss-type purpose-limited product claims. Both of these are formulations of second medical use claims and it is clear that the drafting of them is somewhat similar at a surface level. However, the Board has recognised that the crucial difference between product and process claims, that being the scope of protection they afford, must also apply to these formulations.

Once this proposition is established then the next issue for the Board becomes apparent; if the two classes of claim have different scopes, are those different scopes relevant to whether they cover "the same subject-matter"? The Board found that scope must be relevant. The reasoning of the Board was fairly light but it considered this proposition established by decision T 1391/07.

There is a clear logic to this finding. The rationale for prohibiting double-patenting is that there can be no legitimate interest in an applicant having two patents covering the same thing (i.e. the same subject-matter).

However, if the claims have a different scope then they afford different levels of protection to the underlying invention. A situation could conceivably arise where one of these scopes could be infringed but not the other. It therefore cannot be said that the applicant for the patents has no legitimate interest in obtaining both of them; he clearly does because they give him different, albeit tightly linked, rights.

The Board's comments on the legislator's intent in drafting Article 54(5) to replace the need for the case law derived Swiss-type claims are also interesting. While the legislator may have intended that both types of claim would be the same, they have not been treated as such by the Enlarged Board of Appeal, and now too by the Board of Appeal. While legislative intention has some relevance to interpretation of law, the Board's approach is correct in that if the legislator did not achieve his objective then the EPO should not overstretch to achieve it for him.

This decision ultimately clarifies the scope of the prohibition on double-patenting. Equally importantly it reinforces that Article 54(5) purpose-limited product claims and Swiss-type purpose-limited product claims are not the same thing.

That said, what the precise extent of the differences between the two types of purpose-limited claims are, remains unanswered. For patentees who have cleared the "double patenting" hurdle now clarified by the EPO in this decision and who have obtained both types of claim, questions such as: "do the differences have any practical effect?" and "can they be exploited?" still remain.

In the relatively recent UK case of Ranbaxy (UK) Ltd v AstraZeneca AB [2011] EWHC 1831 (Pat), AstraZeneca was unsuccessful in its arguments where the distinction was sought to be exploited.

Much like the EPO in the case discussed above, in Ranbaxy Mr Justice Kitchin acknowledged there was a difference in scope between the two formats of claim but did not delve any deeper into what that difference could be.  Even if there was a difference it seemed to make no odds as the court found that neither type of claim was infringed.

As filing Swiss-type claims has, since the EPO Technical Board of Appeal's decision G2/08, become a thing of the past, the actual practical distinction between these two types of purpose-limited claims may now remain a matter for academics alone.

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